Study on small seismic isolation table using coil springs

Abstract

In this paper, a new type of small seismic isolation table using coil springs, which has a simple construction and the capability of vibration isolation in every horizontal direction, is proposed. A table board supported with roller bearings is pulled almost vertically toward a base board with four coil springs. The coil springs give horizontal restoring force and friction force to the table board when the table moves relatively to the base board. The trial small seismic isolation table is manufactured, and the resisting force characteristics are measured. The numerical results are derived theoretically and compared with the experimental results. Harmonic response test and seismic response tests are carried out by using a shaking table in order to confirm the effect of vibration isolating under some earthquakes that have several periodic component. The experimental and calculated results show that the maximum response accelerations of the table board with a loaded mass decreased to about 1/10 ~ 1/12 compared to those without the isolation table.